The present invention relates to a transmission and more particularly to a decoupling device for decoupling the transmission from the vehicle driveline. The invention is particularly suited to continuously variable transmissions (CVT) and automatic transmissions.
Most CVT transmissions remain engaged irrespective of the state of the vehicle, and this can cause problems with towing of such vehicles and possible transmission damage.
According to an aspect of the present invention, there is provided a transmission assembly including an output shaft, a vehicle driveline, a decoupling device for disconnecting the vehicle driveline from the output shaft, the output shaft including a conduit for the supply of control fluid to the decoupling device, the decoupling device including at least one component located on or in the output shaft and controlled by fluid pressure provided through said conduit.
According to another aspect of the present invention, there is provided a vehicle including an engine and a transmission assembly as herein specified, wherein the conduit is coupled to the vehicle engine such that control fluid therein is pressurized on the basis of engine output.
In the preferred embodiment, the transmission is a CVT transmission, in which case the decoupling device preferably disconnects the driven pulley from the vehicle driveline.
Advantageously, the decoupling device is located between a driven pulley and a final drive gear to disconnect the driven pulley from the vehicle driveline.
In an alternative embodiment, the transmission is an automatic transmission having discrete gear ratios.
In the preferred embodiment, there is provided means for operating the decoupling device when the engine is stopped and/or no pressure is available.
The present invention provides improved towing performance and can prevent transmission damage of a vehicle being towed. The preferred embodiments do not significantly add to the size of a conventional transmission.